1. Field of the Invention
This invention relates to a multi-circuit hydraulic brake system for automotive vehicles with an anti-skid control system.
2. Description of the Relevant Art
In brake systems of this type, as well as in accordance with German Published Patent Application DE-OS No. P 37 05 311, a separating valve is connected between the master cylinder and the wheel brake cylinder. According to prior art, the following sequence of operation will result during brake slip control: upon pump starting, the separating valve will be closed and the control valve connected between the wheel brake cylinder and storage reservoir will be opened. As such, pressure medium will escape from the wheel brake cylinder resulting in a decrease in braking force. If the braking pressure is re-increased, the control valve will be closed and the separating valve will be opened. The pressure built up by the pump can be metered into the brake circuit by means of a pressure relief valve. The level of pressure buildup by the pump is adjustable by means of a pressure control valve connected between the pump outlet and the storage reservoir. Up to now, the actuation of the pressure control valve was effected in dependence upon the pressure in the master brake cylinder.
A disadvantage of brake systems of this type is the complicated and voluminous structure and the probability of trouble proportional to the number of individual components; any one of which may cause a failure. The effort and expense of assembly and quality control, plus the system's final price are correspondingly high.
It is an object of this invention to increase the ratio of operational reliability in respect to the number of components which up to now have been considered optimal and to reduce the constructional expenditure of the brake system.